A DSATUR-based algorithm for the Equitable Coloring Problem

This paper describes a new exact algorithm for the Equitable Coloring Problem, a coloring problem where the sizes of two arbitrary color classes differ in at most one unit. Based on the well known DSatur algorithm for the classic Coloring Problem, a pruning criterion arising from equity constraints is proposed and analyzed. The good performance of the algorithm is shown through computational experiments over random and benchmark instances.Fil: Méndez-Díaz, Isabel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Computación; ArgentinaFil: Nasini, Graciela Leonor. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, Ingeniería y Agrimensura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Severin, Daniel Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, Ingeniería y Agrimensura; Argentin

Vanadate and bone metabolism: effect on proliferation and mineralization of fish bone-derived cells

Vanadate is known for mimicking insulin action through activation of insulin and/or insulin like growth factor 1 (IGF 1) receptors. Vanadate insulin- like effect on bone-related metabolism has been previously investigated using mammalian in vitro cell systems but other vertebrate systems have rarely been used. We have recently demonstrated the suitability of a fish bone derived cell line (VSa13) to study anti-mineralogenic effects of vanadate. Here, we propose that vanadate stimulation of cell proliferation involves MAPK signalling pathway and IGF 1 receptor activation, while impairment of extracellular matrix (ECM) mineralization is likely to involve both MAPK and PI 3K pathways and insulin receptor activation

Vanadate effects on bone metabolism: fish cell lines as an alternative to mammalian in vitro systems

Vanadate, one of the most relevant forms of vanadium in solution, has been associated with the regulation of various enzyme activities (e.g. phosphatases, ribonucleases, ATPases, etc.) and shown to exhibit important biological effects. Several in vivo and in vitro studies have clearly demonstrated that any deficiency or excess of vanadium can seriously affect bone formation and its metabolism. Bone-related effects result largely from vanadium insulino-mimetic capabilities mediated by specific inhibition of protein tyrosine phosphatases (PTPases) and consequent activation of tyrosine kinase receptors (e.g. insulin receptor). Although mammals have been repetitively shown to be appropriate models to study vanadate mechanisms of action, fish have recently emerged as alternative models. Fish has been recognized as suitable model to study vertebrate bone formation and the natural presence of high quantities of vanadium in water makes it even more suitable to investigate vanadium effect on bone formation. Recent data obtained using fish bone-derived cells revealed that micromolar concentrations (5 mM) of monomeric and decameric vanadate slightly stimulate growth performances while strongly inhibiting extracellular matrix mineralization through mechanisms involving both alkaline phosphatase and MAPK pathways. Recent data obtained in fish cells will be discussed here and further compared to results obtained in mammalian systems

Planning the workday of bus drivers by a graph list-coloring model

In this work, we address the problem of planning the workday of bus drivers in argentinian intercity bus transport companies. In particular, we focus on a company which needs to fulfill roughly 800 trips per day between 3 cities of the Province of Buenos Aires with a stuff of around 200 drivers and 100 buses. Planning consists of assigning one driver to each trip in a way the driver performs all the trips without scheduling conflicts and minimizing the overall amount of overtime among all bus drivers. We model the problem as a particular Graph Coloring Problem and we propose an Integer Linear Programming formulation. Computations experiments show that this formulation outperforms other ones given in the literature for the same problem. In order to address large instances as the one given by the company, we also propose a heuristic algorithm that delivers better solutions than the company actually uses in a reasonably amount of time. The heuristic has two phases where the first one constructs an initial solution and the second one improves the solution iteratively.Fil: Lucci, Mauro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; ArgentinaFil: Nasini, Graciela Leonor. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, Ingeniería y Agrimensura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; ArgentinaFil: Severin, Daniel Esteban. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, Ingeniería y Agrimensura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentin

Impairment of mineralization by metavanadate and decavanadate solutions in a fish bone-derived cell line

Vanadium, a trace metal known to accumulate in bone and to mimic insulin, has been shown to regulate mammalian bone formation using in vitro and in vivo systems. In the present work, short- and long-term effects of metavanadate (containing monomeric, dimeric, tetrameric and pentameric vanadate species) and decavanadate (containing decameric vanadate species) solutions on the mineralization of a fish bone-derived cell line (VSa13) were studied and compared to that of insulin. After 2 h of incubation with vanadate (10 μM in monomeric vanadate), metavanadate exhibited higher accumulation rates than decavanadate (6.85±0.40 versus 3.95±0.10 μg V/g of protein, respectively) in fish VSa13 cells and was also shown to be less toxic when applied for short periods. In longer treatments with both metavanadate and decavanadate solutions, similar effects were promoted: stimulation of cell proliferation and strong impairment (75%) of extracellular matrix (ECM) mineralization. The effect of both vanadate solutions (5 μM in monomeric vanadate), on ECM mineralization was increased in the presence of insulin (10 nM). It is concluded that chronic treatment with both vanadate solutions stimulated fish VSa13 cells proliferation and prevented ECM mineralization. Newly developed VSa13 fish cells appeared to be appropriate in the characterization of vanadate effects on vertebrate bone formation, representing a good alternative to mammalian systems

A Branch and Price Algorithm for List Coloring Problem

Coloring problems in graphs have been used to model a wide range of real applications. In particular, the List Coloring Problem generalizes the well-known Graph Coloring Problem for which many exact algorithms have been developed. In this work, we present a Branch-and-Price algorithm for the weighted version of the List Coloring Problem, based on the one developed by Mehrotra and Trick (1996) for the Graph Coloring Problem. This version considers non-negative weights associated to each color and it is required to assign a color to each vertex from predetermined lists in such a way the sum of weights of the assigned colors is minimum. Computational experiments show the good performance of our approach, being able to comfortably solve instances whose graphs have up to seventy vertices. These experiences also bring out that the hardness of the instances of the List Coloring Problem does not seem to depend only on quantitative parameters such as the size of the graph, its density, and the size of list of colors, but also on the distribution of colors present in the lists.Fil: Lucci, Mauro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Exactas Ingeniería y Agrimensura. Escuela de Ciencias Exactas y Naturales. Departamento de Matemática; ArgentinaFil: Nasini, Graciela Leonor. Universidad Nacional de Rosario. Facultad de Ciencias Exactas Ingeniería y Agrimensura. Escuela de Ciencias Exactas y Naturales. Departamento de Matemática; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Severin, Daniel Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Exactas Ingeniería y Agrimensura. Escuela de Ciencias Exactas y Naturales. Departamento de Matemática; Argentina10th Latin and American Algorithms, Graphs and Optimization Symposium (LAGOS 2019)Belo HorizonteBrasilCoordenação de Aperfeiçoamento de Pessoal de Nivel SuperiorConselho Nacional de Desenvolvimento Científico e Técnologico do BrasilUniversidade Federal de Minas Gerai

Application of low cost technology for the management of irrigation in organic orchards

Throughout history, humans have cyclically return to their old traditions such as the organic orchards. Nowadays, these have been integrated into the modern cities and could supply fresh vegetables to the daily food improving human health. Organic orchards grow crops without pesticides and artificial fertilizers thus, they are respectful with the environment and guarantee the food's safety . In modern society, the application of new technology is a must, in this case to obtain an efficient irrigation. In order to monitor a proper irrigation and save water and energy, soil water content probes are used to measure soil water content. Among them, capacitive probes ,monitored with a specific data logger, are typically used. Most of them, specially the data loggers, are expensive and in many cases are not used. In this work, we have applied the open hardware Arduino to build and program a low cost datalogger for the programming of irrigation in an experimental organic orchard. Results showed that the application of such as low cost technology, which is easily available in the market and easy to understand, everyone can built and program its own device helping in managing water resources in organic orchards

The university radio as a tool for social inclusion: OndaCampus in contexts like the prison and disadvantaged neighborhoods

La evolución de las radios universitarias en España ha conseguido que su carácter formativo se amplíe hasta alcanzar su función social. Si bien las emisoras que pertenecen a las universidades cumplen la función esencial de prestar una formación adicional y práctica al alumnado, también han permitido conectar, de manera real, la institución académica con la ciudadanía. De este modo, surgen iniciativas en las emisoras, en colaboración con algunos servicios universitarios y asociaciones externas a la propia institución docente y científica, que promueven la cultura, la difusión del conocimiento y, como principal factor, la inclusión social de las personas que participan en los mismos. A lo largo de este trabajo, hablamos y analizamos dos iniciativas de carácter social: “La Ventana de la Ciencia”, programa de radio dedicado a la divulgación científica, realizado íntegramente por internos del Centro Penitenciario de Badajoz y el proyecto “E-Misión Color”, cuyo objetivo consiste en empoderar, en materia de comunicación, a los ciudadanos de los barrios más desfavorecidos de la margen de la ciudad de Badajoz. A partir de una recolección de datos y del uso de una metodología cualitativa basada en la entrevista, este estudio permite demostrar las funciones naturales, accidentales y transversales de la radio universitaria. Los datos obtenidos a partir de este trabajo corroboran, en este sentido, el valor de la radio universitaria como herramienta de reinserción y resocialización.The evolution of university radios in Spain has achieved that its formative character is extended to reach its social function. Although the stations belonging to the universities fulfill the essential function of providing additional and practical training to students, they have also made it possible to connect, in a real way, the academic institution with the citizens. In this way, initiatives arise in the stations, in collaboration with some university services and associations outside the teaching and scientific institution itself, which promote culture, the dissemination of knowledge and, as the main factor, the social inclusion of the people who participate in them. Throughout this work, we talk and analyze two initiatives of a social nature: “The window of science”, a radio program dedicated to scientific dissemination, carried out entirely by inmates of the Badajoz Penitentiary Center and the project “E-Mission Color”, Whose objective is to empower, in matters of communication, the citizens of the most disadvantaged neighborhoods on the banks of the city of Badajoz. From a data collection and the use of a qualitative methodology based on the interview, this study allows to demonstrate the natural, accidental and transversal functions of the university radio. The data obtained from this work corroborate, in this sense, the value of university radio as a tool for reintegration and resocialization

Corrosion resistance improvement of Ti-6Al-4V alloy by anodization in the presence of inhibitor ions

Colorful thin oxide films were synthesized by galvanostatic anodization on Ti-6Al-4V alloy. Three different aqueous solutions containing corrosion inorganic inhibitors (Na2MoO4, NaH2PO4 and NH4VO3) were employed for the anodization treatment. The effect of inhibitor anions on the corrosion behavior of the alloy in Ringer solution was studied. Open circuit potential (OCP), Tafel polarization, linear sweep voltammetry (LSV) and chronoamperometry (CA) were performed to evaluate the corrosion performance of the treated electrodes. The incorporation of the inhibitor ions was detected by the release of Mo, V and P through ICP-AES technique. The formed oxides were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results show that compact, amorphous oxides without pores or cracks were obtained independently of the solution used. The sample anodized in Na2MoO4 solution registered the lowest corrosion current density (0.11 μA/cm2), and it was able to protect the alloy even after 168 h of immersion in Ringer solution. No cracks or corrosion products were detected. The XPS analysis reveals the incorporation of molybdenum to the oxide film in the form of Mo6+ and Mo4+.Fil: Martínez, Alejandra Leonor. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; ArgentinaFil: Flamini, Daniel Omar. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; ArgentinaFil: Saidman, Silvana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; Argentin